Particle transport and flow modification in planar temporally evolving mixing layers. II. Flow modification due to two-way coupling

Simulations of two-dimensional, two-way coupled particle-laden mixing layers were performed for particles with various Stokes numbers, at mass loadings between 0.1 and 0.5. This component complements Part I of the study, where particle and fluid transport was analyzed under one-way coupling. Under two-way coupling, the accumulation of particles in the periphery of the Kelvin-Helmholtz vortices results in the formation of intricate undulating patterns, and rupture and break-up of the vortices. At higher mass loadings the vortex structure is completely destroyed. The overall accumulation at the edges of the mixing layer is significantly reduced due to two-way coupling. The rate of evacuation of the vortex core was found to be much slower compared to one-way coupling. In a global sense, particles delay the development of the mixing layer in terms of saturation of the fundamental and the subharmonic modes. Significant generation of small-scale vorticity and higher energy in the small scales is observed at higher mass loadings. Particles are shown to increase the modal kinetic energy dissipation rate. The mean fluid kinetic energy balance shows that most of the kinetic energy exchange between the particle and fluid phases takes place at the edges of the mixing layer. As the mixing layer evolves, the kinetic energy exchange with the particle phase was shown to decrease in importance compared to the other terms in the mean kinetic energy balance; namely, the energy exchange between the mean and the modal fields and the modal transport term. (c) 2006 American Institute of Physics.